Mouse Models for Stem Cell Therapeutic Development

Stem cells have tremendous potential for treating human diseases, as they have the unique capacity to develop into any cell type in the body and to proliferate indefinitely. The development of new therapies based on the transplantation of human stem cells (HuSC) into patients is a major focus of California researchers. A critical step prior to making new HuSC-based therapies available for use in humans is to test their safety and treatment efficacy in research animals that have the relevant disease. The laboratory mouse, widely recognized as the premier mammalian model for studying human disease, is the optimal organism for these preclinical studies. Mice naturally develop many important human diseases, and certain other diseases that afflict humans but normally do not occur in mice can be experimentally induced. While numerous valuable mouse models are currently available, these models must be further developed so that they can accept HuSC transplantation, through suppression of their immune systems. The lack of proven mouse models in which the immune system has been suppressed is a major bottleneck in research to translate discoveries in basic stem cell research to use in the clinic. An additional factor contributing to this bottleneck is a lack of efficient access to mouse models in general. Currently, mouse models are made available from individual laboratories as funds and timelines permit, and, additionally, the mice are generally not bred in quantities or under health conditions suitable for widespread distribution. The recent development at [REDACTED] of immune-deficient mice that support long-term transplantation with HuSCs opens a novel avenue for eliminating the bottleneck of inadequate animal models for preclinical stem-cell studies. At [REDACTED], we will use these immune-deficient strains together with the most valuable existing mouse models of disease to develop a broad array of immune-deficient mouse models of disease. We will also use state-of-the-art facilities to characterize biological traits in these models so that disease progression and the biological response to therapeutic compounds can be accurately assessed. Finally, we will establish and implement mouse production processes for efficient delivery of the desired quantities of mice to California stem cell investigators. It is critically important for CIRM investigators to have the appropriate mouse models to successfully advance therapeutics through the drug development pathway. Overall, this project will significantly accelerate the availability of effective, safe HuSC-based therapies to patients in California and elsewhere.

Statement of Benefit to California:

Stem cells, with their unique capacities to give rise to any cell type and to proliferate indefinitely, have enormous potential for treating human disease. Millions of Californians suffer from the diseases that could be treated effectively through therapies based on transplantation with human stem cells (HuSC). Before HuSC therapies are used in human patients, it is critical to test the safety and efficacy of the therapies using a research animal that has the relevant disease. The laboratory mouse is widely recognized as the most valuable animal model for studying human disease, and reliable mouse models for most of the major human diseases are currently available. However, these models have normal immune systems and are therefore not well suited for testing HuSC therapies, as the immune system recognizes the transplanted stem cells as foreign and attacks them. The lack of mouse models of disease in which the immune system has been suppressed significantly hinders the efforts of investigators in California and elsewhere to develop new HuSC-based disease therapies. An additional impediment is the lack of efficient access to the quantities of mice required for such studies, and to mice whose health, reproducibility, and research effectiveness has been assured. In the proposed project at [REDACTED], we will develop multiple state-of-the-art, immune-deficient mouse models of human disease that can be used for testing HuSC therapies, and we will establish the production processes for making these models readily available to California researchers. This project will benefit Californians by providing broad access to these critical models in the shortest possible timeframe. Further, this project leverages [REDACTED] resident expertise in creating new mouse models and its own investment in state-of-the-art animal production facilities in [REDACTED], allowing California to limit its investment in this type of critical, but costly, infrastructure.

Progress Report:

Year 1

This progress report covers the 12 month period since the funding of this grant titled ‘Mouse Models for Stem Cell Therapeutic Development’. Under this grant awarded TR1-01232 we proposed to eliminate bottlenecks to translation of stem cell research by a) developing a comprehensive collection of standardized mouse models on the appropriate immune backgrounds, and b) establishing production-scale processes to ensure their efficient availability to California researchers.
Aims for year 1 include: 1. completion of validation and characterization of the type 1 diabetes model and its release; 2. optimization of the protocol for induction of Parkinson's disease using the chronic MPTP-probenecid protocol and characterization of the behavioral phenotype; 3. optimization of the Multiple Sclerosis (MS) experimental autoimmune encephalomyelitis (EAE) induction protocol and characterization of the behavioral phenotype; and initiation of the development of the stroke surgical model.
We have completed the development of the streptozotocin induced type 1 diabetes model. We have optimized the concentration and dosing regimen required for induction of chronic hyperglycemia and validated the use of insulin producing cells for amelioration of hyperglycemia. We have also verified the stability of the hyperglycemic phenotype in NSG and their response to the transplantation of insulin producing cells following shipment. Current we have mice being maintained on the shelf in a normoglycemis state to determine the survival time for the graft.
We have completed the optimization of the concentration and dosing regimen for induction of Parkinson’s disease in the NSG mouse using the chronic MPTP and probenecid protocol and we have established the behavioral phenotype of the model. We are currently scaling up the model and validating the phenotype following shipment.
We have completed the optimization of two models for induction of EAE MS using Proteolipid Protein and Myelin-oligodendrocyte glycoprotein. We are now establishing the reproducibility of the models on scale up. The rapid induction hinders the potential to develop this model for shipment and we are currently reviewing options for modifying the model to address this concern.
All the models mentioned above although not yet fully released to the research community are ready for release and we are working with researchers interested in developing the models within their own facilities and researchers who are interested in working with JAX to execute studies using these models.
Due to the unexpected death of our surgeon we adjusted our first year aims regarding surgical models. The initiation of the development of traumatic brain injury (TBI) model was moved to year 1 in place of stroke. This change was made as it allowed us to leverage the expertise of Dr. Hall and our newly hired lab manager. Training has initiated in the surgical manipulation for injury induction and is proceeding without complication.
We have met the primary goals of year 1 have initiated work on goals set for year 2.

Year 2

Under this grant awarded TR1-01232 titled ‘Mouse Models for Stem Cell Therapeutic Development’ we proposed to eliminate bottlenecks to the translation of stem cell research by a) developing a comprehensive collection of standardized mouse models on the appropriate immune backgrounds, and b) establishing production-scale processes to ensure their efficient availability to California researchers.
Year 1 milestones included the release of the streptozotocin induced type 1 diabetes model and this achievement was reported in our year 1 progress report. Year 1 milestones also included the development of a model of Multiple Sclerosis (MS).
At the end of year 1 we reported that we had optimized the induction protocol for both the proteiolipid protein (PLP) and myelin-oligodendrocyte (MOG) induced MS models. We have been able to reproducibly induce disease in both male and female NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. In the PLP model we are able to consistently achieve a pattern of relapsing and remitting disease although the remission is only about 50% of the peak disease severity. We have assessed the efficacy of glatiramer acetate (GA; Copaxone) as a reference compound in the PLP model and determined its effectiveness in reducing the severity of disease in female NSG mice but not in males. In the MOG model of MS we show disease relapse and remission although the changes in disease severity are not as discrete as that observed in the PLP model and may be more correctly labeled a vacillation in disease severity. Although the standard test used in these MS models is disease activity index scoring we sought to develop a less subjective and more rapid test for higher throughput screening of test compounds. We have looked at grip strength and found a reproducible reduction in this parameter in mice induced to disease compared to naïve animals. We also observed a reproducible improvement in grip strength in GA treated animals. Although higher throughput. We may, if time permits, look at locomotor function in these models. We are currently awaiting the pathology report on these models. We have completed the scale up study and the shipping assessment and we are currently finalizing the release of these models.
Year 2 milestones include the release of our chronic (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced Parkinson’s disease model and the release of our stroke model.
We have completed the optimization of our chronic MPTP model and identified that although significant death is observed following twice weekly dosing of MPTP at 27.5mg/kg for 5 weeks (50%) this dose of MPTP provides the most reproducible behavioral changes. On locomotor testing MPTP treated mice showed a consistent increase in clinical signs of anxiety. This is important as this is a feature of the disease observed in human patients and is associated with pathology rather than the trauma of the disease alone. We also showed a reproducible decrease in motor function although interestingly this was seen after an initial observation of improved performance measured by rotarod and open field testing. The initial improvement is likely a phenomenon associated with a compensatory change in gait, such as decreased stride length and increased stride frequency, which masks clinical signs of disease during the early milder phase. Immobility testing by tail suspension showed a significant decrease in movement on tail suspension in MPTP treated male NSG mice but this finding was not reproducible in females. We are awaiting dopaminergic cell counts to see if females have less reproducible cells loss following MPTP treatment. Interestingly, reduced risk of Parkinson’s disease and disease severity is associated with females. The chronic MPTP model of Parkinson’s disease is available to researchers for both shipment to their facility and for execution of studies through our internal service.
Although initially a year 3 milestone we reported at the end of our first year of the award that we had moved TBI to year 2 and stroke to year 3. We have initiated the development of the traumatic brain injury (TBI) protocol. The TBI surgical procedure has been optimized and we have standardized the injury protocol. Using the Precision Instruments automated TBI system we have established mild, moderate, and severe injury profiles.
Earlier than scheduled, the development and standardization of the surgical procedure for stroke induction has been completed. Due to variability in the vasculature of the NSG mouse reproducibility of injury is proving difficult.
We have also initiated the SCI model development and significant progress is being made.
I can report that the adjustment to our proposed milestones has allowed us to remain on schedule for the release of all models proposed in the original grant within the 3 years of the grant award.

Year 3

Under the grant award TR1-01232 titled ‘Mouse Models for Stem Cell Therapeutic Development’ we proposed to eliminate bottlenecks to the translation of stem cell research by a) developing a comprehensive collection of standardized mouse models on the appropriate immune backgrounds, and b) establishing production-scale processes to ensure their efficient availability to California researchers. This was a 3 year award which began November 2009 and was scheduled to conclude October 2012 however following the approval of our request for the extension of the award we are now scheduled to complete the proposed work by October 2013. This report will review the completed objectives and provide an update on those objectives still underway.
The objectives of the study were to develop models of type 1 diabetes (T1D), multiple sclerosis (MS), Parkinson’s disease (PD), stroke, spinal cord injury (SCI), traumatic brain injury (TBI) and myocardial infarct (MI); to characterize these models; and to develop operational processes to make these models available to the research community. Where feasible the models are to be developed in the NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mouse due to its highly immunocompromised status making it a favorable host for human cells and tissues. Additionally, the NSG mouse is also the platform on which our humanized immune system is built and offers the additional benefit of supporting stem cell therapy studies assessing the immunogenicity of novel stem cell therapeutics.
Objectives achieved to date include the release of the streptozotocin (STZ) model of T1D, the experimental autoimmune encephalomyelitis (EAE) myelin oligodendrocyte glycoprotein (MOG) and proteolipid protein (PLP) models of MS and the methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) plus probenecid chronic model of PD.
Development of the SCI model is progressing noting that the surgical procedure has been mastered and technicians have been trained to execute related surgical aftercare and phenotyping tests. Characterization of the model has begun and is expected to be completed Q2.
Development of the stroke middle cerebral artery occlusion (MCAO) model is well underway with the surgical procedure optimization having been completed. Prior to initiating additional staff training our surgical technician is currently executing studies to verify infarct reproducibility.
The loss of our previous surgical team to graduate school has impacted the progression of work initiated on the TBI and MI models, requiring the training of new staff on all procedures from surgery to phenotype analysis. This retraining is underway and will be supported by Dr. Bonnie Lyons, Associate Veterinarian and head of surgical services for The Jackson Laboratory.
It has become clear to us that characterization and optimization of models is only the first step in providing this resource to the research community. The expertise that is developed needs to be adequately shared so as to create redundancy within the JAX in vivo program and maintained so it is always readily available.

Year 4

Under the 3 year grant award TR1-01232 titled ‘Mouse Models for Stem Cell Therapeutic Development’ we proposed to eliminate bottlenecks to the translation of stem cell research by a) developing a comprehensive collection of standardized mouse models on the appropriate immune backgrounds, and b) establishing production-scale processes to ensure their efficient availability to California researchers. This was a 3 year award which began November 2009 and was scheduled to conclude October 2012 however following the approval of our request for the extension of the award we have now completed the proposed work. This report will review the completed objectives.
The objectives of the study were to develop models of type 1 diabetes (T1D), multiple sclerosis (MS), Parkinson’s disease (PD), stroke, spinal cord injury (SCI), traumatic brain injury (TBI) and myocardial infarct (MI); to characterize these models; and to develop operational processes to make these models available to the research community. Where feasible the models have been developed in the NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mouse due to its highly immunocompromised status making it a favorable host for human cells and tissues. Additionally, the NSG mouse is also the platform on which our humanized immune system is built and offers the additional benefit of supporting stem cell therapy studies assessing the immunogenicity of novel stem cell therapeutics.
Objectives achieved to date include the release of the streptozotocin (STZ) model of T1D, the experimental autoimmune encephalomyelitis (EAE) myelin oligodendrocyte glycoprotein (MOG) and proteolipid protein (PLP) models of MS and the methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) plus probenecid chronic model of PD. In this report, we have achieved goals of successfully completing Spinal Cord Injury (SCI) model, Traumatic Brain Injury (TBI) model, middle cerebral artery occlusion (MCAO) model of stroke and myocardial infarct (MI) model. Model reproducibility in each case is supported by histological assessment. All of these four models required surgical expertise obtained through extensive training.
As previously noted, characterization and optimization of models is only the first step in providing this resource to the research community. The expertise that is developed needs to be adequately shared so as to create redundancy within the JAX in vivo program and maintained so it is always readily available.